US3549859A - Self-cleaning oven with smoke eliminator - Google Patents

Description

United States Patent Filed Francis L. Faehling;

Stanley 0. Peterson, Wisconsin Rapids, Wis.

Dec. 18, 1968 Dec. 22, 1970 Preway Inc.

a corporation of Wisconsin Inventors Appl. No.

Patented Assignee SELF-CLEANING OVEN WITH SMOKE ELIMINATOR 1 Claim, 2 Drawing Figs.

US. Cl. 219/393, 23/288: 2l9/4i2 hit. F27d 11/02 Field ofSearch 219/397,

References Cited UNITED STATES PATENTS ll/l 942 Ames 219/392 ll/l952 Ames.... 219/395 1/1960 Walkoe..... 219/393 8/ l 967 Hurko 219/397 2/1969 Hurko et a1 2 l 9/397X FOREIGN PATENTS 2/1940 Switzerland 2 l 9/ 396 Primary Examiner-Velodymyr Y. Mayewsky Altomey-l-lofgren, Wegner, Allen, Stellman and McCord ABSTRACT: A self-cleaning oven having a smoke eliminator with a catalytic element effective on heating and a broil element positioned adjacent the top of the oven and adjacent said smoke eliminator and operable a large part of the time during a self-cleaning cycle to generate sufficient heat to activate the catalytic element directly from the broil element, without any separate heating circuit for the catalytic element.

SELF-CLEANING OVEN WITH SMOKE ELIMINATOR BACKGROUND OF THE INVENTION This invention pertains to self-cleaning ovens and, more particularly, to a smoke eliminator for use with such ovens wherein the heat responsive catalytic element of the smoke eliminator is activated by heat derived from the broil element of the oven.

A majority of the self-cleaning ovens on the market have heat elements operable at a rated voltage of approximately 240 volts, but during a self-cleaning cycle are operated continuously at 120 volts to avoid thermal shock. These ovens, as well as those that operate the broil element at rated voltage periodically during the self-cleaning cycle, have not had provision for activation of the smoke eliminator from heat generated directly by the broil element but have relied upon a separate heater for energizing the catalytic element of the smoke eliminator. This, of course, .requires additional components and circuitry to cause effective operation of the smoke eliminator.

SUMMARY OF THE INVENTION An object of this invention is to provide a new and improved smoke eliminator wherein a catalytic element thereof can be directly activated by heat derived from a broil element constructed and located adjacent the smoke eliminator to provide sufficient heating thereof.

An additional object of the invention is to provide a selfcleaning oven having an outlet passage from the top of the oven chamber, with a smoke eliminator positioned at the entrance to the outlet passage and having a catalytic element effective upon sufiicient heating and a broil unit positioned adjacent the top of the oven chamber and having a plurality of lengths thereof and an interconnecting curved section positioned directly beneath the smoke eliminator whereby intermittent cycling of the broil element at full rated voltage provides sufficient wattage to heat and activate the catalytic element.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of an oven of the built-in type mounted in a cabinet with a part of the oven door broken away; and

FIG. 2 is a vertical section, taken generally along the line 2-2, in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A front trim frame of the self-cleaning oven has a control panel 11 at the upper front thereof mounting suitable control knobs 15 for controlling the various operations of the oven, with a control box 16 located to the rear of the control panel and housing the necessary circuitry. This control box includes circuitry to operate the oven in a self-cleaning cycle. The circuit is well known in the an and includes a timer (not shown) for controlling the length of the self-cleaning cycle and circuitry to operate the broil element at a percentage input of rated voltage.

The oven includes interior walls, including a top wall 20, a bottom wall 21 and a rear wall 22. One of the sidewalls 23 is shown in the drawings. These walls are surrounded by an insulating casing (not shown) to insulate the oven chamber defined by the aforementioned walls from the surrounding cabinet, or other adjacent structure. The top wall 20 of the oven has an opening near the rear thereof to which an upwardly recessed cap 25 is fitted and which defines the entrance of an outlet passage from the oven. An upwardly-opening outlet 26 from the cap connects to other structure (not shown) for conveying gases from the oven.

A smoke eliminator 27 is positioned beneath the opening in the top wall 20 and secured thereto whereby gases leaving the oven must pass through the smoke eliminator in the exhaust path from the oven. This smoke eliminator is necessary in a selfcleanmg oven because of the smoke generated during the high temperature bum-off of material within the oven, and is a commercially available device. A typical device is that offered by the Ucinite Co. and which has a spirally-wound ribbon of stainless steel with a catalytic element disposed within a cylindrical open-ended housing which becomes effective to eliminate smoke upon reaching a predetermined temperature.

The heating of the catalytic element is accomplished without the use of any separate circuitry and solely by the use of a broil element, indicated generally at 30, located adjacent the top wall 20 of the oven and having, in the illustrated embodiment, a series of element lengths 3l-36 for a total of six element lengths which are connected by curved sections 37- --41 disposed alternately at opposite ends of the broil element. As seen in FIGS. I and 2, the interconnecting curved section 38 is disposed directly beneath the smoke eliminator and its catalytic element. This positions a sufficient amount of broil element surface adjacent the smoke eliminator whereby the broil element will heat the catalytic element to render it effective to eliminate smoke. Other broil elements with a different number of lengths could be used.

It has been found that operating the broil element 30 at volts continuously does not provide a high enough surface temperature on the broil element to activate the catalytic element since the conventional output of such a element is approximately 750 watts. With element operated at 240 volts, the element need only operate periodically during the cleaning cycle and more specifically approximately 40 percent of the time or more provides a sufficiently high surface temperature on the broil element to activate the catalytic element of the smoke eliminator. As examples, a 3500 watt broil element has performed satisfactorily operating at 45 50 percent input at rated voltage. Also, a 3000 watt broil element operated at 60 percent input at rated voltage provides approximately 1800 watts and has performed satisfactorily.

We claim:

1. In a self-cleaning oven, a smoke eliminator located beneath an outlet passage for the oven and having a catalytic oxidation element effective upon reaching a predetermined temperature, an electric broil element having a rated voltage of approximately 240 volts mounted in the upper part of said oven and having a pair of adjacent lengths and a curved interconnecting section directly disposed and closely spaced beneath the smoke eliminator in unobstructed heat exchange relation therewith, and electrical means for operating the broil element intermittently in a self-cleaning cycle at approximate ly 40 percent or more input at rated voltage to provide the heat needed to activate the catalytic element.

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